1. Field of the Invention
This invention relates to liquid flow control means, and, in particular, to means for controlling the filling of a receptacle, such as a dishwasher tub, and the heating of the liquid therein.
2. Description of the Prior Art
In one conventional dishwasher structure, a tub is provided having a sump portion in which dishwashing liquid is collected for recirculation as by being sprayed against the dishes being washed in the apparatus. The quantity of dishwashing liquid is conventionally controlled by filling the tub to a preselected normal full level from a pressurized liquid source. One example of such an apparatus is shown in U.S. Pat. No. 3,331,374 of Bruce E. Stewart et al, owned by the assignee thereof. In said patent, the liquid level and flow control includes a drain outlet and a return outlet, with a solenoid operated valve for selectively closing the drain outlet. A float is attached to the valve to open it as the result of a high liquid level condition in the tub, even though the solenoid is de-energized to prevent draining of the liquid from the tub. A heater is provided for heating the liquid during preselected cycles of the dishwashing operation.
A number of different control valves for use in controlling liquid fill in different devices are known in the art. Illustratively, a safety cutoff device for fuel supply lines shown in William C. Coleman U.S. Pat. No. 2,174,055 is used in connection with a delivery of liquid fuel to a gas burning appliance. The Coleman device utilizes a float operated linkage to close the liquid inlet valve under certain operating conditions.
Hans Erik Sebastian Hiort af Ornas discloses, in U.S. Pat. No. 2,395,968, a dishwasher having a steam generator providing means for urging the washing liquid through a sprinkler. The use of the steam provides a successive heating of the washing water so as to provide different temperatures of different portions of the washing water.
In U.S. Pat. No. 2,471,778 of Luther Ringer, a fluid responsive control apparatus is shown wherein float means are provided responding to the rising and falling of the fluid level in a container for controlling introduction and removal of the fluid relative to the container and maintaining a desired fluid level therein.
In U.S. Pat. No. 2,547,098, Carl A. Smith et al disclose an electromagnetic valve having manual means for actuating the valve in event of failure of electrical power.
Thomas B. Chace et al, in U.S. Pat. No. 2,548,651, show a fluid control system for laundering apparatus, having means for controlling the temperature of the washing liquid, and utilizing float actuated means for controlling a drain valve. A cup-shaped member is provided which operates to cut off liquid delivery, and a weight controlled unit is provided to stop delivery notwithstanding continued operation of the cup-shaped member.
Hanes E. S. Hiort af Ornas, in his subsequent U.S. Pat. No. 2,618,281, shows another dishwashing device operable by variable pressure steam to provide repeated sprinkling of the dishes in the washing chamber. In his further U.S. Pat. No. 2,621,666, Hiort af Ornas discloses a dishwashing machine having heating elements for the washing fluid container and the rinsing water vessel and means for successive heating of the washing fluid and the rinsing water.
James B. Kirby, in U. S. Pat. No. 2,877,778, shows a dishwashing machine having a manually operable mechanism for actuating a drain valve therein. A heater is provided for rapidly heating the water in the compartment to a suitable rinsing temperature. The heater is connected so as to operate only when the spray head motor is operated.
George B. Klaber, in U.S. Pat. No. 2,937,014, shows a float valve for controlling liquid delivery in a fuel supply line.
In Australian Pat. No. 263,486, of Modern Equipment Company Limited, a dishwashing machine is shown wherein a float is provided in a separate chamber adjacent the dishwasher tub for controlling energization of a heater in that chamber. The heater is controlled by a switch operated by closing of the door to the dishwashing compartment and the float when the water in the chamber reaches a preselected level. The float controls the switch so as to discontinue energization of the heater in the event the liquid level drops below a preselected level and the float may be used to control other operations of the dishwasher.
John H. Spragins, in U.S. Pat. No. 2,664,094, shows a level control for controlling the level of dishwasher liquid in a separate well communicating with the tub for providing steam into the washing compartment.
James H. Bear, in U.S. Pat. No. 3,083,717, shows a dishwashing machine having a float which energizes a heater when the water level in the heating tank reaches a preselected level. When the volume in the tank reaches the desired volume, the float de-energizes the supply valve while heating of the water continues until the water reaches a preselected temperature with a thermostat maintaining the temperature thereafter. Manual operation of a valve handle discharges the heated water into a dishwashing chamber and a pump motor is energized to effect a spraying of the dishes therein. A switch also controlled by the float disconnects the heater whenever the water level in the heating tank drops below a preselected low level while the rinse water is being withdrawn to prevent further operation of the heater subsequent to the transfer of the water from the heating tank to the dishwashing chamber.
Donald S. Cushing shows, in U.S. Pat. No. 3,439,687, a control system for an automatic dishwasher having a fluid switch ameliorating a malfunction of either the water valve or the fill switch controlling the liquid delivery to the dishwasher by de-energizing the water valve and permitting energization of a drain solenoid to open a drain valve.
In U.S. Pat. No. 3,610,271 of Wilbur W. Jarvis, owned by the assignee hereof, a variable liquid level control for use with liquid receiving devices, such as dishwashers and the like, is disclosed as being controlled by a float having a plurality of buoyant compartments, with means for varying the buoyancy of the float by selectively closing the compartments. The float operates a switch to terminate the fill operation when the liquid level in the washing chamber reaches a preselected level.
Eugene W. Scott, in U.S. Pat. No. 3,829,636, shows an overflow control dashpot-type float for a dishwasher switch assembly for controlling an externally mounted overflow switch.
In a copending application owned by the assignee hereof of Phillip P. Johnson and William T. Lampman, Ser. No. 683,952 filed May 6, 1976, concurrently herewith (PA-4870), for a Receptacle Fill Apparatus, an apparatus similar to that disclosed herein, but without the liquid heater and liquid heater control means hereof, is disclosed and claimed.